This invention relates to phosphated alumina.
Supported catalysts such as chromium oxide on silica can be used to prepare olefin polymers in a hydrocarbon solution to give a product having excellent characteristics from many standpoints. Supported transition metal oxide catalysts can also be used to prepare olefin polymers in a slurry system, wherein the polymer is produced in the form of small particles of solid material suspended in a diluent. This process, frequently referred to as a particle-form process, has the advantage of being less complex.
Recently, it has been discovered that aluminum phosphate can be prepared in a manner which provides an outstanding support for olefin polymerization catalysts. However, the aluminum phosphate must be prepared in a fairly complex manner in order to preserve the pore structure and therefore, it is relatively expensive. It is known that alumina, which is quite inexpensive, can be used as a support for chromium catalysts. However, in fact, alumina does not generally give a very satisfactory support.
McDaniel, U.S. Pat. No. 4,397,765 (Aug. 9, 1983), discloses a quite satisfactory support made by phosphating alumina. This support is inexpensive to prepare and gives excellent results compared with alumina. It does, however, fall short of giving a productivity as high as the more expensive aluminum phosphate. Also, certain properties such as melt flow are not as good with aluminum phosphate as the support.